Alkaline rechargeable batteries and lithium ion rechargeable batteries are widely used as the power source of portable devices, electric tools, or electric vehicles. Nickel metal hydride rechargeable batteries, among others, have a relatively high energy density and excellent durability, and have found increasing applications particularly in electric vehicle power source systems.
The main compositions of nickel metal hydride rechargeable battery are, generally, a positive electrode formed of a three-dimensional porous metal body filled with nickel hydroxide and other components, and a negative electrode formed of a core material which is a porous metal sheet such as punched metal and electrode mixture paste composed of hydrogen-absorption alloy and other components applied on the core material. Of these two, the negative electrode is attracting attention because of its potential for continuous production and possibilities of highly efficient manufacture. More specifically, a known technique for adjusting the coating thickness of electrode mixture paste is, after immersing the core material in electrode mixture paste to apply the paste on both sides of the core material, to pass the paste-coated core material through a gap between a pair of scraper tools, the surface of the core material making contact with several projections provided to the scraper tools to restrict the position of the core material so that it passes through the center between the tools. (see, for example, Patent Document 1).    [Patent Document 1] Japanese Patent Laid-Open Publication No. 9-134722